JavaFx：TreeTableView奇怪的NullpointerException

Question

我注意到TreeTableView有一個奇怪的NPE

如果您在沒有行的表中雙擊，就會發生這種情況。 附上一張截圖，以顯示我的確切意思。

我純粹來自JavaFx，與我的代碼無關。 我也做了研究，沒有發現與此相關的任何東西。

這是重現它的簡單代碼：

控制器：

public class Controller implements Initializable {
    @FXML
    private TreeTableColumn<Model, String> column;
    @FXML
    private TreeTableView<Model> treeTable;

    @Override
    public void initialize(URL location, ResourceBundle resources) {
        TreeItem<Model> root = new TreeItem<>(new Model("Root"));
        treeTable.setRoot(root);
        column.setCellValueFactory(value -> value.getValue().getValue().textProperty());

    }

    private class Model {
        private StringProperty text;

        Model(String text) {
            this.text = new SimpleStringProperty(text);
        }

        public StringProperty textProperty() {
            return text;
        }

        public String getText() {
            return text.get();
        }

        @Override
        public String toString() {
            return getText();
        }
    }
}

.fxml：

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.TreeTableColumn?>
<?import javafx.scene.control.TreeTableView?>
<?import javafx.scene.layout.AnchorPane?>
<AnchorPane xmlns="http://javafx.com/javafx"
            xmlns:fx="http://javafx.com/fxml"
            fx:controller="stackoverflow.treeview.Controller">
    <TreeTableView fx:id="treeTable">
        <columns>
            <TreeTableColumn fx:id="column" text="Test"/>
        </columns>
    </TreeTableView>
</AnchorPane>

如果雙擊紅色區域，將引發NPE。

堆棧跟蹤：

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
    at com.sun.javafx.scene.control.behavior.TreeTableRowBehavior.handleClicks(TreeTableRowBehavior.java:89)
    at com.sun.javafx.scene.control.behavior.CellBehaviorBase.simpleSelect(CellBehaviorBase.java:259)
    at com.sun.javafx.scene.control.behavior.TableRowBehaviorBase.doSelect(TableRowBehaviorBase.java:120)
    at com.sun.javafx.scene.control.behavior.CellBehaviorBase.mousePressed(CellBehaviorBase.java:150)
    at com.sun.javafx.scene.control.behavior.TableRowBehaviorBase.mousePressed(TableRowBehaviorBase.java:64)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:95)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
    at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.event.Event.fireEvent(Event.java:198)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
    at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:381)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:417)
    at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:416)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
    at com.sun.glass.ui.View.notifyMouse(View.java:937)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
    at java.lang.Thread.run(Thread.java:745)

Java版本：1.8u121

作為一種解決方案，我將接受任何確實有效的解決方法，或者接受任何解釋/ javafx錯誤報告，以表明他們正在使用該方法，或者在以下版本中進行了修復。

Answer 1

在沒有列的空白處單擊時，最終單擊TreeTableRow 。 顯然，控件的行為類中存在一個錯誤，這意味着它無法處理包含null項目的行。 如果單擊列的空白區域，則不會看到此錯誤，因為單擊的是TreeTableCell ，其行為類似乎沒有遇到相同的問題。 不知道確切的區別在哪里，但是我只快速瀏覽了一下源代碼。

如@kleopatra所述，一種阻止引發異常的方法是在TreeTableRow中添加一個事件過濾器，該事件過濾器消耗對空行的雙擊。

var table = new TreeTableView<String>();
table.setRowFactory(ttv -> {
    var row = new TreeTableRow<String>();
    row.addEventFilter(MouseEvent.MOUSE_PRESSED, event -> {
        if (row.getItem() == null && event.getClickCount() % 2 == 0) {
            event.consume();
        }
    });
    return row;
});

注意：您需要clickCount % 2 == 0因為當點擊計數為偶數時，行為類將嘗試訪問TreeItem 。